The Source
The patient force of the decay — the poison door's own, the serpent-folk distillers' shelf, and the one that sets the terms.
The Yield
A culture gives a season's wait for a set-terms' worth; the wait is the whole argument; the argument is the one that wins by arithmetic.
In the Workshop
The culture is the material of the slow argument: the poison does not chase, the poison waits, and the waiting is the one the distiller has to pay for — the season is the price, and the price is the one the terms are set on.
Cost band: master (the reagent grade) — on the ladder in The Maker's Hand, the material is the floor, and the floor is the one the mine or the marsh or the tree has to give. Recipes that take it: distillation, the poison school's reagent spells